Not Applicable.
This invention generally relates to the field of hematology. More particularly, this invention relates to a hematology control composition made from a unique combination of elements which simulates vertebrate white blood cells. Further, the present invention relates to a method of making such a hematology control composition.
Instrumentation useful in analyzing blood components and chemistry has been used for many years. Over time, the accuracy and sensitivity of such hematology instruments have steadily advanced. Early hematology instrumentation has evolved into relatively complex machinery which analyzes the discrete components of blood based upon the intricate and subtle characteristics of its components. The most recently developed automated hematology instrumentation is capable not only of detecting red blood cells and platelets, but also is capable of conducting a multi-part analysis of human white blood cells.
Methods for analyzing blood cells involve an examination of both the electrical and optical properties the cell. For instance, the Beckman-Coulter(trademark) five-part white blood cell analysis instrument utilizes three different technologies for blood cell analysis. These technologies include electrical impedance, a DC mathematical manipulation commonly referred to as conductance, and laser technology. Instruments made by other manufacturers, such as Abbott Diagnostics(trademark), Technicon(trademark), and TOA(trademark), also use electrical impedance, DC conductance and/or laser technology, individually or in combination.
Although the basic types of electronic technology utilized may appear similar or identical among machinery made by different manufacturers, each manufacturer has a unique implementation for the instrument hardware and software that is required to analyze blood cells. The individual implementation of these technologies by various manufacturers has resulted in a wide array of reagents and methodologies, each one specific to a particular instrument of a particular manufacturer. Accordingly the complexity and expense associated with the use of such hematology instrumentation can be significant. There is no single reagent and no single methodology which may be used with a plurality of instruments.
In order to ensure that a particular hematology instrument is working properly, governments have mandated that there be a method to verify the integrity of the instrument using a blood control composition. To provide accurate data, a control composition should contain components which represent each of the cellular elements of fresh blood, as well as a liquid component to serve as a suspending media, a function similar to that performed by human plasma. This synthetic plasma usually contains components that are identical or similar to, or function identical to or similar to, native plasma. To achieve this end, the components of synthetic plasma include inorganic salts, organic and/or inorganic buffers, and a viscous material for maintaining homeostasis which is similar to native plasma proteins. Additionally, the control composition should have a shelf life that is sufficient for the composition to be used for days, weeks, or months while the consistency of instrument performance is preserved over time.
Methods for preparing hematology control compositions are dependent upon the hardware and software design of the specific instrument with which the control is to be used, as well as the requirement for extended shelf life. Particles in blood control compositions that behave like human white blood cells, red blood cells, or platelets on a Coulter(trademark) type instrument may not accordingly behave on other instruments, such as instruments manufactured by Abbott Laboratories(trademark), Technicon(trademark), or TOA(trademark). Moreover, because particles in blood control compositions usually are modified forms of various types of blood cells, they often do not behave like living native fresh blood cells. As a result, human white blood cells fixed with a cross-linking agent such as glutaraldehyde may behave like a neutrophil on an Abbott(trademark) instrument, but behave like cellular debris on a Coulter(trademark) instrument. Similarly, specially treated and cross-linked red blood cells from non-mammalian vertebrates may look like mononuclear cells on one type of hematology instrument and look like lymphocytes on another.
Accordingly, there remains a need in the hematology instrumentation industry for a hematology control composition which functions as a leukocyte subpopulation analogue and contains one or more non-cellular components. Such non-cellular components exhibit enhanced viability and shelf-life. Prior to the present invention, non-cellular components and cellular components have not been used in combination with treated native white cell components for use as white blood cell subpopulations in a blood control for 5-part white blood cell analyzers.
Accordingly, in one of its aspects, the present invention provides a hematology control composition having at least one non-animal component which functions as a leukocyte analogue for at least one subpopulation of leukocytes.
In another of its aspects, the present invention provides a hematology control composition having at least one non-animal component which functions as a leukocyte analogue for a plurality of subpopulations of leukocytes.
In yet another aspect, the present invention provides a hematology control composition having at least one non-animal component which function as a leukocyte analogue for at least one subpopulation of leukocytes, wherein the control composition may be made more easily and less expensively than prior art control compositions.
In an additional aspect, the present invention provides a method of making a hematology control composition having the qualities disclosed herein.
According to the present invention, the foregoing and other aspects are achieved by a hematology control composition having a plurality of components including a synthetic plasma component, a red blood cell component, a platelet component and a leukocyte component. The leukocyte component includes at least one subpopulation having particles derived from other than white blood cells.
Additional aspects of the present invention are achieved by a method of making a hematology control composition. The method of the present invention includes providing a synthetic plasma solution, adding a human red blood cell component to the plasma solution, adding a sufficient volume of surrogate or real platelets to the plasma solution and adding a volume of particles representing a plurality of human white blood cell subpopulations. At least one of the white blood cell subpopulations includes particles from other than white blood cells.
The present invention is directed to a white blood cell control composition which simulates animal white blood cells and is made from a unique combination of components. The present invention further is directed to a method of making the novel white blood cell control composition of the present invention. The particular embodiments and methods described herein are intended in all respects to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its scope.
Preserved or aldehyde-fixed native white blood cell preparations include the true white cell type(s), such as a preserved neutrophil that is displayed on an instrument as a neutrophil, and simulating a cell type, such as a preserved white cell that looks like a neutrophil on an Abbott Model 3500 but looks like cellular debris or platelet aggregates on a Coulter Model MAXM instrument.
Simulated white blood cells from fixed red blood cells or commercially prepared micro beads may be produced by a number of methods. Fixed red blood cells are described in U.S. Pat. Nos. 5,380,644, 4,704,364 and 3,873,467. Micro beads are divided into non-biological and biological organic particles. Non-biological organic particles may be commercially prepared from base materials such as polystyrene, polyvinyltoluene, and styrenedivinylbenzene. The use of a single non-biological particle in a blood control is described in U.S. Pat. No. 3,977,995. Commercially prepared micro beads are also defined as those particles with a biological origin as plant pollen. All commercially prepared micro-beads will be hereafter referred to as xe2x80x9corganic particlesxe2x80x9d.
The methods of preserving vertebrate white cells for simulated or non-simulated white cells include those in a series of patents including U.S. Pat. Nos. 5,672,474 and 5,858,790. Processes and methods for simulating white blood cells from non-white blood cells including organic particles, as can be seen in U.S. Pat. Nos. 3,977,995, 5,380,644, 4,704,364.
The control composition of the present invention utilizes white blood cells to correctly represent (non-simulate) as well as simulate human white blood cell populations. The control composition of the present invention also utilizes non-white blood cell particles to simulate human white blood cell subpopulations. It is well-known that human blood includes five subpopulations of leukocytes. In accordance with the present invention, at least one of the five subpopulations of leukocytes is simulated by non-white blood cell sources. These non-white blood cell particles include latex beads, plant pollen, fixed red blood cells or other particles exhibiting the size and other characteristics of the subpopulation to be simulated. While latex beads, plant pollen and fixed red blood cells are disclosed as non-white cell particles, it is to be understood that other particles also may work as leukocyte subpopulation analogs. Depending on the instrument upon which the control composition is to be used and the desired application to be achieved, various combinations of non-white blood cell particles and white blood cell particles can be utilized in the control of the present invention to achieve a blood control which simulates human blood.
In one application, the control composition may include latex beads or plant pollen to represent vertebrate lymphocytes, monocytes and granulocytes. The control may also utilize cross-linked white blood cells to represent other leukocyte subpopulations. A synthetic plasma replacement is also used and human red blood cells function as the human red blood cells of the blood. Preserved red blood cells to simulate vertebrate platelets. The overall control product, therefore, closely simulates substantially all components of human blood.
The present invention is designed for use on a multi-part blood analyzer, although it also is envisioned for use on other blood analyzers. For a multi-part white blood cell analyzer, latex beads may be used to provide the lymphocyte subpopulation and the mononuclear subpopulation, depending on the size of the beads to be used. It is to be understood that latex beads can be sized to achieve the desired simulated subpopulation as the instrument and circumstances may dictate.
The method for making the control composition of the present invention includes adding the red blood cell component and a synthetic plasma replacement into a sterile bottle. A sufficient volume of surrogate platelets are then added. The white blood cell components for the subpopulations of the control are then added to the mixture. The resulting control can then be preserved for later use.
The following are examples of combinations of components that may be used to prepare white blood cell control compositions in accordance with the present invention as well as methods for making the control compositions. It will be understood and appreciated that these examples are in no way intended to limit the scope of the present invention but are merely offered by way of illustration.